Daughter Cells

Cancer Cell Mitosis
These cancer cells are undergoing cytokinesis (cell division). Cytokinesis occurs after nuclear division (mitosis), which produces two daughter nuclei. Mitosis produces two identical daughter cells. MAURIZIO DE ANGELIS/Science Photo Library/Getty Images

Daughter Cells

Daughter cells are cells that result from the division of a single parent cell. They are produced from the division processes of mitosis and meiosis. Cell division is the reproductive mechanism, whereby living organisms grow, develop, and produce offspring. At the completion of the mitotic cell cycle, a single cell divides forming two daughter cells. A parent cell undergoing meiosis produces four daughter cells.

While mitosis occurs in both prokaryotic and eukaryotic organisms, meiosis occurs in eukaryotic animal cells, plant cells, and fungi.

Daughter Cells in Mitosis

Mitosis is the stage of the cell cycle that involves the division of the cell nucleus and the separation of chromosomes. The division process is not complete until after cytokinesis, when the cytoplasm is divided and two distinct daughter cells are formed. Prior to mitosis, the cell prepares for division by replicating its DNA and increasing its mass and organelle numbers. Mitosis involves several phases: prophase, metaphase, anaphase, and telophase. During these phases, chromosomes are separated, moved to opposite poles of the cell, and contained within newly formed nuclei. At the end of the division process, duplicated chromosomes are divided equally between two cells. These daughter cells are genetically identical diploid cells that have the same chromosome number and chromosome type.

Somatic cells are examples of cells that divide by mitosis. Somatic cells consist of all body cell types, excluding sex cells.

Cancer cells dividing by mitosis may produce three or more daughter cells. These cells may have either too many or not enough chromosomes due to irregular division of the cell.

Daughter Cells in Meiosis

In organisms that are capable of sexual reproduction, daughter cells are produced by meiosis. Meiosis is a two part division process that produces gametes. The dividing cell goes through prophase, metaphase, anaphase, and telophase twice. At the end of meiosis and cytokinesis, four haploid cells are produced from a single diploid cell. These haploid daughter cells have half the number of chromosomes as the parent cell and are not genetically identical to the parent cell. In sexual reproduction, haploid gametes unite in fertilization and become a diploid zygote. The zygote continues to divide by mitosis and develops into a fully functioning individual.

Daughter Cells and Chromosome Movement

How do daughter cells end up with the appropriate number of chromosomes after cell division? The answer to this question involves the spindle apparatus. The spindle apparatus consists of microtubules and proteins that manipulate chromosomes during cell division. Spindle fibers attach to replicated chromosomes, moving and separating them when appropriate. The mitotic and meiotic spindles move chromosomes to opposite cell poles, ensuring that each daughter cell gets the correct number of chromosomes.

The spindle also determines the location of the metaphase plate. This centrally localized site becomes the plane on which the cell eventually divides.

Daughter Cells and Cytokinesis

The final step in the process of cell division occurs in cytokinesis. This process begins during anaphase and ends after telophase. In cytokinesis, the dividing cell is split into two daughter cells with the assistance of the spindle apparatus. In animal cells, the spindle apparatus determines the location of an important structure in the cell division process called the contractile ring. The contractile ring is formed from actin microtubule filaments and proteins, including the motor protein myosin. Myosin contracts the ring of actin filaments forming a deep groove called a cleavage furrow. As the contractile ring continues to contract, it divides the cytoplasm and pinches the cell in two along the cleavage furrow.

This process of cytokinesis is different in plant cells. Plant cells do not contain asters, star-shaped spindle apparatus microtubules, which help determine the site of the cleavage furrow. In fact, no cleavage furrow is formed in plant cell cytokinesis. Instead, daughter cells are separated by a cell plate, which is formed by vesicles that are released from Golgi apparatus organelles. The cell plate expands laterally and fuses with the plant cell wall forming a partition between the newly divided daughter cells. As the cell plate matures, it eventually develops into a cell wall.

Daughter Chromosomes

The chromosomes within daughter cells are termed daughter chromosomes. Daughter chromosomes result from the separation of sister chromatids, which occurs in anaphase of mitosis and anaphase II of meiosis. Daughter chromosomes develop from the replication of single-stranded chromosomes during the synthesis phase (S phase) of the cell cycle. The single-stranded chromosomes become double-stranded chromosomes that are held together at a region called the centromere. Double-stranded chromosomes are known as sister chromatids. Sister chromatids are eventually separated and divided between newly formed daughter cells. Each separated chromatid is known as a daughter chromosome.